Composition for making wettable cathode in aluminum smelting

ABSTRACT

Compositions for making wettable cathodes to be used in aluminum electrolysis cells are disclosed. The compositions generally include titanium diboride (TiB 2 ) and metal additives. The amount of selected metal additives may result in production of electrodes having a tailored density and/or porosity. The electrodes may be durable and used in aluminum electrolysis cells.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation of and claims priority to U.S.patent application Ser. No. 14/549,628, filed Nov. 21, 2014, which is acontinuation of Ser. No. 13/472,005, filed May 15, 2012, which is acontinuation of U.S. patent application Ser. No. 12/845,540 filed Jul.28, 2010, now U.S. Pat. No. 8,211,278, issued Jul. 3, 2012, which is anon-provisional of U.S. Provisional Application No. 61/229,083, filedJul. 28, 2009, all of which are incorporated herein by reference intheir entirety.

BACKGROUND

Aluminum electrolysis cells employ a system of anodes and cathodes.Typically, the cathode is produced from amorphous carbon, which isdurable and inexpensive. However, a cathode or a cathode component thathas better aluminum wettability and permits closer anode-cathode spacingby reducing movement of molten aluminum could improve the thermodynamicefficiency. Titanium diboride (TiB₂) is wettable by aluminum metal, andefforts have been made to produce cathodes from TiB₂. See, U.S. Pat. No.4,439,382 to Joo, U.S. Pat. No. 2,915,442 to Lewis, U.S. Pat. No.3,028,324 to Ransley, U.S. Pat. No. 3,156,639 to Kibby, U.S. Pat. No.3,314,876 to Ransley, Apr. 18, 1967, U.S. Pat. No. 3,400,061 to Lewis,U.S. Pat. No. 4,071,420 to Foster, Canadian Pat. No. 922,384, Mar. 6,1973, and Belgian Pat. No. 882,992. However, it is believed that no TiB₂cathodes are currently in commercial use.

SUMMARY OF THE DISCLOSURE

Compositions for making wettable cathodes to be used in aluminumelectrolysis cells are disclosed. One embodiment discloses a compositiongenerally comprising titanium diboride (TiB₂). In some embodiments, acomposition consists essentially of titanium diboride and at least onemetal additive, the balance being unavoidable impurities. In someembodiments, the metal additive includes Co, Fe, Ni, and W, amongothers.

In one approach, an electrode is produced from the composition. Theelectrode includes (i) titanium diboride, (ii) from about 0.01 to about0.75 wt. % metal additives, and (iii) the balance being unavoidableimpurities. In one embodiment, the metal additives are selected from thegroup consisting of Fe, Ni, Co, and W, and combinations thereof. In oneembodiment, the electrode includes not greater than about 0.65 wt. % ofthe metal additives. In other embodiments, the electrode includes notgreater than about 0.60 wt. %, or not greater than about 0.55 wt. %, ornot greater than about 0.50 wt. %, or not greater than about 0.45 wt. %,or not greater than about 0.40 wt. %, or not greater than about 0.35 wt.% of the metal additives. In one embodiment, the electrode includes atleast about 0.025 wt. % of the metal additives. In other embodiments,the electrode includes at least about 0.050 wt. %, or at least about0.075 wt. %, or at least about 0.10 wt. %, of the metal additives. Theuse of these amounts of metal additives in combination with the lowamounts of unavoidable impurities at least partially facilitates theproduction and use of electrodes having suitable density, electrical andcorrosion resistance properties.

For example, the electrodes may be fabricated from powders havingcompositions similar to that described above. In one embodiment, theelectrodes may be fabricated using conventional powder sinteringprocesses, such as hot pressing or pressureless sintering, among otherpowder sintering processes. Sintering is a method of making objects frompowder, and includes heating at least one material in a sinteringfurnace below its melting point (solid state sintering) until theparticles of the powder adhere to one other. Densification aids, such asthe metal additives described above, may be incorporated to produce adense-fired titanium diboride composition body. The densification aidsmay facilitate sintering by producing a liquid phase during heating,enabling the energy (e.g., temperature and/or pressure) to be loweredand the total amount of metal additives to be reduced/restricted.

With respect to the sintering temperature, the electrodes may beproduced by sintering at temperatures of between about 1400° C. to about2100° C. In some embodiments, the temperature may be in the range offrom about 1600° C. to about 2000° C. In one embodiment, pressureassisted densification processes are used to produce the electrodes. Inthese embodiments, pressures of from about 70 to at least about 350kg/cm² may be applied during sintering.

As described above, the use of the metal additives in theabove-described quantities facilitates densification of the powders intoelectrodes. In one embodiment, the metal additives are selected suchthat the produced electrode has a density of from about 80% to about 99%of its theoretical density. The production of electrodes having adensity within this range, facilitates long-term use in aluminumelectrolysis cells (e.g., using carbon anodes and/or inert anodes). Ifthe density is too high, the electrodes may crack during use in thecell. If the density is too low, the material may not have sufficientdurability.

A theoretical density (ρ_(theory)) is the highest density that amaterial could achieve as calculated from the atomic weight and crystalstructure.

$\rho_{theory} = \frac{N_{c}A}{V_{c}N_{A}}$

Where:

-   -   N_(c)=number of atoms in unit cell    -   A=Atomic Weight [kg mol⁻¹]    -   V_(c)=Volume of unit cell [m³]    -   N_(A)=Avogadro's number [atoms mol⁻¹]        For the purposes of this patent application the theoretical        density is 4.52 g/cc, which is the approximate theoretical        density of pure TiB₂.

In one embodiment, the electrode has a density of at least about 85% ofits theoretical density (i.e., ≥3.842 g/cc). In other embodiments, theelectrode has a density of at least about 86% (≥3.887 g/cc), or at leastabout 87% (≥3.932 g/cc), or at least about 88% (≥3.978 g/cc), or atleast about 89% (≥4.023 g/cc), or at least about 90% (≥4.068 g/cc) ofits theoretical density. In one embodiment, the electrode has a densityof not greater than about 98.0% of its theoretical density (≤4.430g/cc). In other embodiments, the electrode has a density of not greaterthan about 97.5% (≤4.407 g/cc), or not greater than about 97.0% (≤4.384g/cc), or not greater than about 96.5% (≤4.362 g/cc), or not greaterthan about 96.0% (≤4.339 g/cc), or not greater than about 95.5% (≤4.317g/cc), or not greater than about 95.0% (≤4.294 g/cc) of its theoreticaldensity. In some embodiments, the electrodes have a density in the rangeof from about 90% to 95% of its theoretical density (4.068 g/cc to 4.294g/cc), such as from about 91% to 94% of its theoretical density (4.113g/cc to 4.249 g/cc).

Electrodes having a density of 80-99% of theoretical may have a porositysuitable for use in an aluminum electrolysis cell. Total porosity isrelated to the percent of the theoretical density. For example, if amaterial has a density of about 90% of its theoretical density, it hasabout 10% total porosity (100%−90%=10%). That is, the 100% theoreticaldensity of an object minus the actual density of the object equals itstotal porosity (TD−AD=TP). The total porosity is the combined amounts ofthe open (apparent) porosity and the closed porosity (TP=OP+CP). Anapparent porosity of a material can be determined via Archimedesprinciple as embodied in ASTM C373-88(2006) Standard Test Method forWater Absorption, Bulk Density, Apparent Porosity, and Apparent SpecificGravity of Fired Whiteware Products.

Generally, electrodes produced using the present compositions mayrealize an apparent porosity of about 0.01 to about 20%. Incontradistinction to the conventional wisdom, it has been foundelectrodes having a high porosity and low density were durable in use inan aluminum electrolysis cell setting, as illustrated in the belowexamples. In one embodiment, the apparent porosity is in the range of0.03-10%. In another embodiment, the apparent porosity is in the rangeof 0.04-5%. In another embodiment, the apparent porosity is in the rangeof 0.05-4%.

Methods for producing the electrodes may include selecting theappropriate amount of metal additive relative to the density required.In one embodiment, and with reference now to FIG. 1, a method (100) mayinclude selecting a metal additive selected from the group consisting ofFe, Ni, and Co, and combinations thereof (110), selecting a densityand/or porosity of an electrode to be produced (120), selecting anamount of the metal additive to achieve the selected density and/orporosity (130), blending the selected amount of metal additive with aTiB₂ powder to produce a blended powder composition (140), and producingan electrode from the blended composition (150), wherein the electroderealizes an actual density and/or porosity that is substantially similarto the selected density and/or porosity. In one embodiment, the densityis selected. In one embodiment, the porosity is selected. In oneembodiment, both the density and porosity are selected, with densitybeing the primary consideration and the porosity being the secondaryconsideration. In one embodiment, both the density and porosity areselected, with porosity being the primary consideration and the densitybeing the secondary consideration. In one embodiment, both the densityand porosity are selected, with both the density and porosity being ofequal importance. In turn, the electrode may be used as one of a cathodeand an anode in an aluminum electrolysis cell. The use may includepassing electricity through the electrode while the electrode is incommunication with a molten salt bath of the aluminum electrolysis cell.In response, Al₂O₃ of the molten salt bath may be reduced to aluminummetal. In one embodiment, the electrode remains whole and absent ofdelamination and/or cracking for at least 120 days of continuous use inthe aluminum electrolysis cell.

To achieve the selected density, a certain amount of metal additivecombinations may be employed. For example, compositions for theelectrode may include at least one of the metal additives of Fe, Ni, Coand W and in a range of from about 0.01 wt. % to about 0.35 wt. %, thebalance being TiB₂ and unavoidable impurities, wherein the total amountof metal additives does not exceed 0.75 wt. %. In one embodiment, thecomposition includes 0.01 to 0.10 wt. % each of Fe, Ni, and Co, and 0.01to 0.35 wt. % of W, the balance being TiB₂ and unavoidable impurities,wherein the total amount of metal additives does not exceed 0.55 wt. %.In another embodiment, the composition includes 0.01 to 0.075 wt. % eachof Fe, Ni, and Co, and 0.01 to 0.20 wt. % of W, the balance being TiB₂and unavoidable impurities, wherein the total amount of metal additivesdoes not exceed 0.375 wt. %. In another embodiment, the compositionincludes 0.01 to 0.06 wt. % each of Fe, Ni, and Co, and 0.01 to 0.175wt. % of W, the balance being TiB₂ and unavoidable impurities, whereinthe total amount of metal additives does not exceed 0.35 wt. %.

In one approach, an electrode include 0.01 to 0.14 wt. % Fe, 0.01 to0.14 wt. % Ni, 0.01 to 0.14 wt. % Co, and 0.01 to 0.45 wt. % W, thebalance being TiB₂ and unavoidable impurities, wherein the total amountof metal additives does not exceed 0.75 wt. %. In one embodiment, theelectrode includes not greater than 0.10 wt. % each of Fe, Ni, and Co.In another embodiment, the electrode includes not greater than 0.07 wt.% each of Fe, Ni, and Co. In another embodiment, the electrode includesnot greater than 0.05 wt. % each of Fe, Ni, and Co. In one embodiment,the electrode includes not greater than 0.30 wt. % W. In one embodiment,the electrode includes not greater than 0.20 wt. % W.

As used herein, “unavoidable impurities” and the like mean constituentsthat may be included in a composition (e.g., an electrode) other thanthe metal additives and TiB₂ described above. Unavoidable impurities maybe included in the composition due to the inherent manufacturingprocesses used to produce the composition. Examples of unavoidableimpurities includes O and C, among others. With respect to oxygen, thiselement may be present as an impurity in amounts of up to about 2.0 wt.%. In one embodiment, not greater than about 1.5 wt. % O is included inthe composition. In other embodiments, not greater than about 1.25 wt. %O, or not greater than about 1.0 wt. % O, or not greater than about 0.75wt. % O, or not greater than about 0.5 wt. % O, or even less, isincluded in the composition. In some instance, the oxygen level in anelectrode may be approximately 0.5 wt. % so as to avoid abnormal graingrowth during production of the electrode.

With respect to carbon, this element may be present as an unavoidableimpurity in amounts of up to about 1.0 wt. %. In one embodiment, notgreater than about 0.9 wt. % C is included in the composition. In otherembodiments, not greater than about 0.8 wt. % C, or not greater thanabout 0.7 wt. % C, or not greater than about 0.6 wt. % C, or not greaterthan about 0.5 wt. % C, or even less, is included in the composition.

A mix and match of the metal additives may be incorporated in acomposition. For example, a composition may include only one, two orthree additives instead of the four described above. In thesesituations, the additives may be included in the composition in amountssimilar to those described above, and the composition may potentially beadjusted to include slightly more of these additives to account for theremoval of the other additive(s). In some embodiments, substitutes forFe, Ni, Co and/or W may be employed, such as Cr, Mn, Mo, Pt, Pd, to namea few. These metal additive substitutes may be employed in addition to,or as a substitute for, the principle metal additives of Fe, Ni, Co, orW.

The electrodes may be used as an anode or cathode in an aluminumelectrolysis cell. In one embodiment, the electrode is a cathode. Insome embodiments, the plates may be used as cathodes in a verticalconfiguration, a horizontal configuration, or inclined configuration(e.g., drained), among others. In one embodiment, the electrode iswettable, meaning that the produced material during electrolysis (e.g.,aluminum) may tend to stick to the surface of the electrode duringelectrolysis operations.

In some embodiments, the compositions may be used to produce othercomponents of an aluminum electrolysis cell, such as cellsuperstructures, protection tubes, and other applications in aluminumsmelting or molten aluminum processing in general. In one embodiment,thermocouple protection tubes may incorporate the compositions disclosedherein. In another embodiment, the compositions may be used for theconstruction of a cell sidewall. In some instances, the compositions areable to provide electrical polarization and/or corrosion resistantproperties, among others. In some examples, the compositions may be usedas a coating or as dopants in the manufacturing of a part, among otherforming techniques. For example, the compositions may be included asadditives in a powder production process. In another example, thecompositions may be added during the processing of fired parts. In otherexamples, the compositions may be incorporated as dopants during thephysical fabrication of a part (e.g., cell sidewall, protection tubes).

Products utilizing the disclosed composition may be fabricated intovarious geometries including tubes, plates, rods, to name a few. Thesize and shape of the final product may vary, depending on the requiredelectrical and mechanical properties of the cathode within the aluminumelectrolysis cell. Examples of electrode plate sizes include squareplates of having a length/width of about 12 inches and a thickness ofabout 0.25 inch or 0.5 inch, and rectangular billets having about a 4inch width, about an 8 inch length, and thickness of about 0.25 or 0.5inch. In some embodiments, a rectangular plate is about 12 inches inwidth, about 16 inches in length, and about 0.25 or 0.5 inch thick. Inone embodiment, a rectangular plate is about 15 inches in width, about22 inches in length, and is about 1 or 2 inch thick.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is flow chart illustrating one embodiment of a method forproducing electrodes having a selected density.

DETAILED DESCRIPTION Example 1

Three different TiB₂ powders having the chemical make-up identified inTable 1, below, are produced by blending TiB₂ powders (e.g., via aV-blender) with various other powders (all values are approximate.Composition D is pure TiB₂ powder containing no metal additives. Variousplates are made from Compositions A-D by pressing the compositions intoplate form using a commercial-scale hot-press.

TABLE 1 Chemical Makeup of Plates A-D Compo- Compo- Compo- Compo-Material (wt. %) sition A sition B sition C sition D Fe 0.14 0.08 0.05Negligible Ni 0.16 0.08 0.04 Negligible Co 0.16 0.08 0.04 Negligible W0.49 0.31 0.16 Negligible TiB₂ and Balance Balance Balance BalanceUnavoidable Impurities Ave. density 98.9% 98.2% 94.9% 68.8% (% oftheoretical) Bulk density (g/cc) 4.47 4.44 4.29 3.11 Apparent Porosity,% 0.07 0.09 0.13 28.6  Total Metal Additives 0.95% 0.55% 0.29%   0% (wt.%)

Plates made from compositions A-C are exposed to a molten salt bath of a10,000 ampere pilot-scale aluminum electrolysis cell. The plates madefrom Composition A fail the testing, showing splitting/delamination.There is a mixed failure rate among plates made from Composition B. Theplates made from composition C all pass the test, in that they surviveabout 120 days of testing without significant loss in thickness andwithout splitting/delamination.

Plates made from Composition D, i.e., pure titanium diboride, aremachined into test coupons (e.g., 2″×2″×0.5″), and the test coupons areexposed a molten aluminum bath having a salt cover in an aluminacrucible. The temperature of the molten aluminum was comparable to theconditions used in the aluminum electrolysis cell using inert anodes(e.g., in the range of 840-910° C.). The test coupons were exposed tothe molten aluminum for about 480 hours. After the exposure period, thetest coupons are removed hot from the crucible and air quenched. Thetest coupons are examined both by macroscopic inspection and bymicrostructure analysis (e.g., via SEM metallography). A test coupon“passes” if it is (a) intact as shown via macroscopic inspection, and(b) there is no visually apparent cracking due to aluminum filledcracks, as shown via the microstructure analysis. If either criteria isnot met, the test coupon is considered a “fail”. The test coupons madefrom Composition D failed, show grain boundary attack and disintegrationafter anywhere from 7 to 20 days of testing, illustrating the inadequacyof pure TiB₂ electrode plates.

With respect to Plates A and B, it is theorized, but not being bound bythis theory, that higher concentration of additives such as the likes ofNi, Co, Fe and/or W, may have led to stress corrosion cracking. Thehigher additive levels may have also led to potential volumetricexpansion reactions between the commonly-used metals and aluminum duringmetal making. However, when the metal additive levels are low enough,stress corrosion cracking is not realized (e.g., due to insufficientmaterials to react with the aluminum metal of the bath).

Plates having too high of a theoretical density, i.e., plates made fromComposition A, and some made from Composition B, fail the test. Thisindicates that the theoretical density should be below about 98%.Indeed, plates made from composition C, which have a density of about95% of theoretical, were successful in passing the pilot testing. Thus,it is anticipated that plates having a density in the range of 90-98% oftheoretical may be effectively used as electrodes in an aluminumelectrolysis cell. The noted metal additives may be useful in producingsuch plates and with the appropriate porosity.

This data also suggests that the total amount of metal additives shouldbe less than 0.55 wt. %. However, it is anticipated that higher amountsof metal additives (e.g., up to about 0.75 wt. % total) could beemployed in some circumstances. The data also shows that at least somemetal additives are required; plates made from pure TiB₂ (Composition D)were the worst performing, indicating that at least some metal additiveis required.

Example 2

Similar to Example 1, various powder blends are produced by blending.The weight percent of the metal additives of the various blended samplesare provided in Table 2, below, the balance being TiB₂ and unavoidableimpurities. TiB₂ powder samples are pressed into plate form using alab-scale, hot-press. After pressing, the plates are machined into testcoupons (e.g., 2″×2″×0.5″).

TABLE 2 Chemical Makeup of Samples 1-9 Total Ave. Metal Density ApparentMaterial Add. (% of Porosity Sample (weight %) (wt. %) theoret.) (%)Result 1 0.125 Ni 0.125 97.2 0.09 Pass 2 0.25 Ni 0.25 98.5 0.23 Pass 30.063 Fe 0.063 88.9 3.79 Pass 4 0.125 Fe 0.125 97.0 0.10 Pass 5 0.25 Fe0.25 98.0 0.05 Pass 6 0.50 Fe 0.50 98.8 0.12 Fail 7 0.6 W 0.60 61.9 37.2Fail 8 0.5 Fe + 0.6 W 1.1 99.6 0.07 Fail 9 0.05 each of Fe, 0.30 97.80.18 Pass Ni, Co + 0.15 W

The test coupons are exposed to a molten aluminum bath having a saltcover in an alumina crucible. The temperature of the molten aluminum wascomparable to the conditions used in aluminum electrolysis cellsemploying inert anodes (e.g., in the range of 840−910° C.). The testcoupons were exposed to the molten aluminum for about 480 hours. Afterthe exposure period, the test coupons are removed hot from the crucibleand air quenched. The test coupons are examined both by macroscopicinspection and by microstructure analysis (e.g., via SEM metallography).A test coupon “passes” if it is (a) intact as shown via macroscopicinspection, and (b) there is no visually apparent cracking due toaluminum filled cracks, as shown via the microstructure analysis. Ifeither criteria is not met, the test coupon is considered a “fail”.

Plates having too high of a theoretical density, i.e., plates made fromsamples 6 and 8 failed the test. However, plates having a density belowabout 98.5%, but above about 88.9% (of theoretical) were able to passthe test. Similarly, plates having too low of a of density, i.e., platesmade from sample 7, failed the test. This data suggests that any of themetal additives of Fe, Ni, and/or Co may be selected as the metaladditive so long as the end products have a density of from about 85% toabout 98.5% of the theoretical density. In some instances, W and/orother substitutes, described above, may be used in place of and/or inaddition to the Fe, Ni, and Co metal additives. This data suggests thatthe total amount of metal additives should be less than 0.50 wt. %.However, it is anticipated that higher amounts of metal additives (e.g.,up to about 0.75 wt. % total) could be employed in some circumstances.

While various embodiments of the present disclosure have been describedin detail, it is apparent that modifications and adaptations of thoseembodiments will occur to those skilled in the art. However, it is to beexpressly understood that such modifications and adaptations are withinthe spirit and scope of the present disclosure.

What is claimed is:
 1. A component, comprising: 0.01 to not greater than0.45 wt. % metal additives, the balance being TiB₂ and unavoidableimpurities, wherein the unavoidable impurities make up less than 2 wt. %of the component; wherein the metal additives at least include chromium(Cr), wherein the chromium content of the component is not greater than0.35 wt. %; wherein the component is crack-free and has a density of atleast 90% to not greater than 98% of its theoretical density, andwherein the component has an apparent porosity of 0.05% to 4%.
 2. Thecomponent of claim 1, further wherein the component comprises a geometryselected from the group consisting of: a tube, a plate, a rod.
 3. Thecomponent of claim 1, wherein the component is configured as anelectrode for use in an aluminum electrolysis cell.
 4. The component ofclaim 1, wherein the metal additives further include one or more of Fe,Ni, Co, and W.
 5. The component of claim 1, wherein the metal additivesfurther include one or more of Mn, Mo, Pt, and Pd.
 6. An electrode foruse in an aluminum electrolysis cell, the electrode comprising: 0.01 toless than 0.5 wt. % metal additives, the balance being TiB₂ andunavoidable impurities, wherein the unavoidable impurities make up lessthan 2 wt. % of the electrode; wherein the metal additives at leastinclude chromium (Cr), wherein the chromium content of electrode is notgreater than 0.35 wt. %; wherein the electrode is crack-free and has adensity of at least 90% to not greater than 98% of its theoreticaldensity, and wherein the component has an apparent porosity of 0.05% to4%.
 7. The electrode of claim 6, wherein the electrode is configured asa cathode in an aluminum electrolysis cell.
 8. A method comprising: (a)blending a first powder comprising TiB₂ with a second powder comprisinga selected amount of metal additives to make a TiB₂ composition, theTiB₂ composition comprising: from 0.01 to not greater than 0.45 wt. % ofthe metal additives, the balance being TiB₂ and unavoidable impurities,wherein the unavoidable impurities make up less than 2 wt. % of theelectrode, wherein the metal additives at least include chromium (Cr),wherein the chromium content of electrode is not greater than 0.35 wt.%; and (b) producing a TiB₂ component from the TiB₂ composition; whereinthe TiB₂ component is crack-free and has a density of at least 90% tonot greater than 98% of its theoretical density, and wherein thecomponent has an apparent porosity of 0.05% to 4%.
 9. The method ofclaim 8, wherein the producing step further comprises: pressing the TiB₂composition; and sintering the pressed TiB₂ composition to yield theTiB₂ component.
 10. The method of claim 8, wherein the method comprisesforming the TiB₂ component, the TiB₂ component comprising a geometryselected from the group consisting of: a plate, a rod, and a tube. 11.The method of claim 8, wherein the producing step further comprises:pressureless sintering the TiB₂ composition to yield the TiB₂ component.12. The method of claim 8, wherein the producing step further comprises:sintering the TiB₂ composition at a temperature of between 1400° C. to2100° C.
 13. The method of claim 12, wherein the producing step furthercomprises: pressing the TiB₂ composition at a pressure from 70 kg/cm³ toat least 350 kg/cm³.
 14. The method of claim 8, wherein the metaladditives further include one or more of Mn, Mo, Pt, and Pd.
 15. Themethod of claim 8, wherein the metal additives further include one ormore of Fe, Ni, Co, and W.
 16. An electrode, comprising: 0.025 to 0.10wt. % metal additives, wherein the metal additives at least include Cr;the balance being TiB₂ and unavoidable impurities, wherein theunavoidable impurities make up less than 2 wt. % of the component;wherein the component has a density of 88.9% to 98.5% of its theoreticaldensity, and wherein the component has an apparent porosity of 0.05% to4%.
 17. The electrode of claim 16, wherein the metal additives furtherinclude one or more of Mn, Mo, Pt, and Pd.
 18. The electrode of claim16, wherein the metal additives further include one or more of Fe, Ni,Co, and W.